Power regulating device for controlling exposing means and fixing means in electrophotographic copying apparatus

Abstract

The power regulator of the present disclosure is operated by a source of D.C. power for controlling the A.C. power to be supplied to an exposing device and to a fixing device. It comprises a first circuit for operating the exposing device, a second circuit for operating the fixing device, a switching circuit for alternately operating the first and second circuits and a third circuit for operating the fixing device independently of the operation of the switching circuit so that the fixing device may be warmed up by the operation of third circuit during the operation of the exposing device.

What is claimed is: 
     
       1. An improved control means in an electrophotorgraphic copying apparatus having an exposing means provided with a lamp element for exposing an original to be copied, an operating means for operating said exposing means, a fixing means provided with a heating element for heating a copy material for fixing thereon a pattern of said original and a control means for controlling the electric power to be supplied to said fixing means in accordance with the variations of temperature in said fixing means, said control means comprising a power limiting means which limits said electric power to a predetermined level during the operation of said exposing means when said electric power to be supplied to said fixing means in accordance with said variations of said temperature in said fixing means is greater than said predetermined level. 
     
     
       2. An improved control means as claimed in claim 1, wherein said apparatus includes an AC power source for supplying AC power to said fixing means and said control means includes a detecting means for detecting said variations of said temperature in said fixing means, a power control means connected to said detecting means for supplying a variable portion of each half cycle of said AC power to said fixing means in accordance with said temperature detected by said detecting means. 
     
     
       3. An improved control means as claimed in claim 1, wherein said apparatus includes an AC power source for supplying AC power to said fixing means and said control means coupled a variable portion of each half cycle of said AC power to said fixing means in accordance with said variations of said temperature in said fixing means, said power limiting means limits said variable portion of each half cycle of said AC power supplied to said fixing means by said control means during said operation of said exposing means when said electric power to be supplied to said fixing means in accordance with said variation of said temperature in said fixing means is greater than said predetermined level. 
     
     
       4. An improved control means as claimed in claim 1, wherein said apparatus includes an AC power source for supplying AC power to said fixing means and said controlling means includes: a detecting means for detecting said variation of said temperature in said fixing means;   a power control means connected with said detecting means for supplying a variable portion of each half cycle of said AC power to said fixing means in accordance with said variation of said detecting temperature detected by said detecting means; and   said power limiting means for limiting said variable portion of each half cycle of said AC power controlled by said power control means during said operation of said exposing means when said electric power to be supplied to said fixing means controlled by said power control means is greater than a predetermined level.   
     
     
       5. An improved control means in an electrophotographic copying apparatus having means for illuminating an original to be copied, means for actuating said illuminating means, means for heating a copy material and means for controlling operations of said heating means in relation to variations of temperature in said heating means, wherein said apparatus includes AC power source for supplying AC power to said fixing means and said controlling means comprises: a temperature detecting circuit for detecting said temperature in said heating means and for producing a temperature signal indicative of said detected temperature;   a reference circuit for producing a reference signal corresponding to a predetermined temperature in said heating means;   a comparator circuit for comparing said reference signal with said temperature signal and for producing a different signal indicative of the difference between said reference signal and said temperature signal;   a gate circuit connected to said comparator circuit for producing a control signal whose phase is shifted in relation to the phase of the AC electric power to be supplied to said heating means and the degree of said shift being in relation to said difference signal, said control signal supplied to said heating means so as to supply said heating means with said electric power upon receipt of said control signal; and   a regulator circuit connected to said comparator circuit for limiting said difference signal produced by said comparator circuit during the operation of said illuminating means when said electric power to be supplied to said heating means in relation to said difference signal is greater than said predetermined level which indicates the maximum of said electric power to be supplied to said heating means during said operation of said illuminating means.   
     
     
       6. In an electrophotographic copying apparatus having exposing means provided with lamp element for exposing an original to be copied, operating means for operating said exposing means, fixing means provided with heating element for heating a copy material for fixing thereon a pattern of said original, and a power regulator operated by source of D.C. power for regulating A.C. power provided from a source of A.C. power to said exposing means and said fixing means, said power regulator comprising; (a) first means for producing first signal upon receipt of D.C. power towards said exposing means for supplying part of the A.C. power from said A.C. power source to said exposing means;   (b) second means for producing second signal upon receipt of D.C. power towards said fixing means for supplying A.C. power from said A.C. power source to said fixing means;   (c) switch means for alternately providing said D.C. power to said first and second means; and   (d) third means for providing said D.C. power towards said second means for supplying another part of A.C. power from said A.C. power source to said fixing means independently of the operation of said switching means, whereby said fixing means is actuated during the operation of said first means.   
     
     
       7. A power regulator as claimed in claim 6, wherein said second signal is variable with respect to temperature in said fixing means whereby said A.C. power supplied to said fixing means is varied in relation to change in said second signal so as to maintain the temperature in said fixing device approximately in a predetermined temperature. 
     
     
       8. A power regulator as claimed in claim 6, wherein said second means comprising; (a) a temperature detecting circuit for detecting temperature in said fixing means and for producing temperature signal indicative of the detected temperature;   (b) a reference circuit for producing reference signal indicative of a predetermined temperature in said fixing means;   (c) a comparator circuit for comparing said reference signal with said temperature signal and for producing a diference signal indicative of a difference between said reference signal and said temperature signal; and   (d) a gate circuit connected to said comparator circuit for producing a control signal whose phase is shifted in relation to the phase of said A.C. power and the degree of said shift being in relation to said difference signal, said control signal being applied to said fixing means whereby said fixing means is provided with said A.C. power upon receipt of said control signal.   
     
     
       9. A power regulator as claimed in claim 8, wherein said comparator circuit produces said difference signal only when the temperature signal is lower than tha reference signal. 
     
     
       10. A power regulator as claimed in claim 9, wherein said comparator circuit includes a capacitor for charging a current flowing through said comparator circuit, whereby said difference signal is a voltage signal produced across said capacitor. 
     
     
       11. A power regulator as claimed in claim 10 further comprising a threshold circuit connected to said gate circuit for producing a threshold voltage signal therefrom to said gate circuit, whereby said difference signal applied to said gate circuit passes, when the voltage of said difference signal reaches the threshold voltage signal, through said gate circuit for producing said control signal. 
     
     
       12. A power regulator as claimed in claim 11 further comprising a timing pulse producing circuit connected to said gate circuit for producing timing pulse signals indicative of zer-cross points after every half cycle in said A.C. power, so as to discharge the capacitor in said comparator circuit at every zero-cross points and to start charging the capacitor from every zero-cross points, whereby said control signal is produced within every half cycle, and with the phase thereof being shifted with respect to the phase of said timing pulse signal between two neighboring timing pulse signals. 
     
     
       13. A power regulator as claimed in claim 12, wherein said exposing means including a triac element which controls, upon receipt of said control signal, the amount of A.C. power between minimum and maximum by the degree of shifted phase in said control signal. 
     
     
       14. A power regulator as claimed in claim 8, wherein said first means comprising a drive circuit which produces a pulsating signal to said exposing means. 
     
     
       15. A power regulator as claimed in claim 14, wherein said exposing means including a triac element which controls, upon receipt of said pulsating signal, the amount of A.C. power between minimum and maximum by the degree of shifted phase in said pulsating signal. 
     
     
       16. A power regulator as claimed in claim 14, wherein said switching means is coupled to said D.C. power source for alternately providing D.C. power to said drive circuit and to said comparator circuit. 
     
     
       17. A power regulator as claimed in claim 8, wherein said third means including a variable resistor for regulating a current flow therethrough. 
     
     
       18. A power regulator as claimed in claim 17, wherein said variable resistor is connected between said D.C. power source and said comparator circuit.